Mass Loss from Giant Stars
Envelope of red giant very loosely held
Star is so big, gravity very weak at the surface
Degenerate core makes nuclear “thermostat” sluggish
Core doesn’t quickly expand and cool when fusion is to fast
Energy can be generated in “thermal pulses”
Low temperature opaque envelope can also “oscillate”
Energy is transmitted in “pulses” as envelope expands and
Main cause of “Variable Stars”
Some Red Giants have very strong stellar winds
ejecting envelopes, forming “Planetary Nebulae
PN called this because some looked like planets in poor
PN don’t have anything to do with formation of planets